Corrected entry: When Carl and Lenny are talking about the brain switching ceremony in Moe's Bar they speak with each others voices. For this to happen they would have to have switched vocal chords too.

Correction:This is speculation at best, not a mistake, since there's never been a brain switch to prove this. Plus, the vocal chord is controlled by muscles to change speech, and the muscles are controlled by the brain. This is why people can impersonate other people's voice (or at least change their own voice).

This is a mistake for the introduction for the later episodes. When Homer screams, he turns round. You see this in a wide shot. There are no boxes to the right of the door in the garage. However, two just appear out of thin air when he runs through the garage.